Previous to this commit, testing easily reproduced a failure where the
seqno would apparently arrive after the IRQ associated with it, with test programs as simple as:
for (;;) {
glCopyPixels(0, 0, 1, 1);
glFinish();
}
Various workarounds we've seen for previous generations didn't work to
fix this issue, so until new information comes in, replace the IRQ
waits on the BLT ring with polling.
Signed-off-by: Eric Anholt <eric at anholt.net>
---
drivers/gpu/drm/i915/intel_ringbuffer.c | 14 ++++++++++++++
1 files changed, 14 insertions(+), 0 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index c3f0c7b..51ba68b 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -793,6 +793,17 @@ ring_add_request(struct intel_ring_buffer *ring,
}
static bool
+gen7_blt_ring_get_irq(struct intel_ring_buffer *ring)
+{
+ /* The BLT ring on IVB appears to have broken synchronization
+ * between the seqno write and the interrupt, so that the
+ * interrupt appears first. Returning false here makes
+ * i915_wait_request() do a polling loop, instead.
+ */
+ return false;
+}
+
+static bool
gen6_ring_get_irq(struct intel_ring_buffer *ring, u32 gflag, u32 rflag)
{
struct drm_device *dev = ring->dev;
@@ -1558,5 +1569,8 @@ int intel_init_blt_ring_buffer(struct drm_device *dev)
*ring = gen6_blt_ring;
+ if (IS_GEN7(dev))
+ ring->irq_get = gen7_blt_ring_get_irq;
+
return intel_init_ring_buffer(dev, ring);
}
--
1.7.7.3
